This sound like you can hear a difference between 120 and 240? I know both have different dual DAC chips. One is Wolfson and the other is Cirus logic(240).
I have only demoed the AK series, and I could not distinguish between 120 and 240 based on my demo. I did distinguish between 100 vs 120 or 240. It was pretty obvious to my ears 120 or 240 sounded a lot better. Not sure if the 100 was the 22ohm version or the MK2.
Fwiw I upgraded from ak100 to ak120 to ak240. For me the change from ak120 to ak240 was MUCH MORE pronounced than from ak100 to ak120.